The main thrust of the proposed work is the design and development of new synthetic methods and reagents and their application to the synthesis of cytotoxic sesquiterpenes, sesquiterpene synthons, and related potential cancer chemotherapeutic agents. Proposed work includes: A) To extend the strategy which we have successfully employed in the synthesis of damsinic acid and confertin to the more highly functionalized pseudoguaianes; B) to continue studies on the olefin metathesis strategy for germacrane synthesis; C) to explore the viability of a divinylcyclopropane rearrangement strategy for the synthesis of phorbols; D) to explore the synthetic and mechanistic ramifications of an olefin metathesis-transannular ene strategy for the synthesis of transfused ring systems.